Motor neuron disease with slow eye movements and vertical gaze palsy.

Two middle-aged patients with motor neuron disease showed common eye movement disorders and intellectual impairment in the later stage of the illness. Eye movement disorders were characterized by slow saccades and vertical glaze palsy, which seemed to be supranuclear ophthalmoplegia. Neuropathological examination of one patient revealed degeneration of the substantia nigra without pathological changes in the ocular motor nuclei, in addition to findings compatible with motor neuron disease. These cases appear to raise a possibility of a distinct group of multiple system degenerations.